1// JavaScript using node-sqlite3
2const sqlite3 = require('sqlite3').verbose();
3
4let db = new sqlite3.Database('./your_database.db', (err) => {
5    if (err) {
6        console.error(err.message);
7    }
8    console.log('Connected to the SQlite database.');
9});
10
11let sql = `
12SELECT customer_id, COUNT(visit_id) AS count_no_trans
13FROM Visits
14LEFT JOIN Transactions ON Visits.visit_id = Transactions.visit_id
15WHERE Transactions.transaction_id IS NULL
16GROUP BY customer_id;`;
17
18// Execute SQL query
19let customerVisits = db.all(sql, [], (err, rows) => {
20    if (err) {
21        throw err;
22    }
23    rows.forEach((row) => {
24        console.log(`${row.customer_id} - ${row.count_no_trans}`);
25    });
26});
27
28db.close((err) => {
29    if (err) {
30        console.error(err.message);
31    }
32    console.log('Close the database connection.');
33});

using System.Data;
using System.Data.SQLite;

class Program
{
    static void Main()
    {
        string connectionString = "Data Source=your_database.db;Version=3;";
        using (SQLiteConnection connection = new SQLiteConnection(connectionString))
        {
            connection.Open();

            string query = "SELECT customer_id, COUNT(visit_id) AS count_no_trans FROM Visits WHERE NOT EXISTS (SELECT 1 FROM Transactions WHERE Visits.visit_id = Transactions.visit_id) GROUP BY customer_id;";
            using (SQLiteCommand command = new SQLiteCommand(query, connection))
            {
                using (SQLiteDataReader reader = command.ExecuteReader())
                {
                    while (reader.Read())
                    {
                        Console.WriteLine($"customer_id: {reader["customer_id"]}, count_no_trans: {reader["count_no_trans"]}");
                    }
                }
            }
        }
    }
}